It's not entirely clear what can cause depression, though a number of things are often linked to its development. It is believed depression is a result of complex interaction and combination of biological, psychological, and social factors. Certain Life Events - Experiencing difficulties such as unemployment, being in an abusive or uncaring relationship, loneliness, prolonged work stress, for a long period of time are likely to cause depression. In addition, recent events such as lose of a loved one or a combination of long term and recent events can also ‘trigger' depression.
Family History of Depression (Genetics) - It has been observed that in some families depression occurs generation after generation, which points to both genetic and parental factors. However, it does not mean that it can't occur in people who have no family history of depression.
Serious Medical Illness – Often physical changes in the body impact mental changes. Medical illnesses or the stress of dealing with medical illnesses such as cancer, a heart attack and hormonal disorders can cause depression, making the sick person unwilling to care for his or her physical needs and thus aggravating the situation.
Personality Issues – People with low self-esteem or those with pessimistic outlook about the world in general or those who are easily overwhelmed by stress, are prone to depression.
Drug Abuse - More than 30% of people with substance abuse problems also experience symptoms of clinical depression.
Certain Medication - Depression is a side effect of many medications including drugs such as Accutane to treat acne. Depression is also a possible side effect of many drugs used to treat conditions such as anxiety, insomnia, high blood pressure and menopausal symptoms